<ul class="nav nav-tabs">
  <li role="presentation" {% if helper_action == 'index' %}class="active"{% endif %}><a href="{% url 'helper_index' %}">常见问答 F.A.Q</a></li>
  <li role="presentation" {% if helper_action == 'student_guide' %}class="active"{% endif %}><a href="{% url 'helper_guide_student' %}">学生使用演示</a></li>
</ul>
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